One conventional cartridge that is detachably mounted in a body of an image forming apparatus is configured of a toner case that accommodates toner, and a process case in which the toner case is detachably mounted (see Japanese Patent Application Publication No. 2011-203493). In this conventional image forming apparatus, a photosensitive drum provided in the process case, and a sensor gear is provided on the toner case. The sensor gear has a contact protrusion and is capable of rotating irreversibly in one direction. When the cartridge is mounted in the body of the image forming apparatus, the sensor gear is driven to rotate by a driving force inputted from the body of the image forming apparatus. When the toner case is a new product, the contact protrusion will contact an actuator provided in the body as the sensor gear rotates, enabling the image forming apparatus to acquire information on the toner case, such as whether the toner case is new.